71 research outputs found
Boosting the performance of the ASTRI SST-2M prototype: reflective and anti-reflective coatings
ASTRI is a Flagship Project of the Italian Ministry of Education, University
and Research, led by the Italian National Institute of Astrophysics, INAF. One
of the main aims of the ASTRI Project is the design, construction and
verification on-field of a dual mirror (2M) end-to-end prototype for the Small
Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array.
The ASTRI SST-2M prototype adopts the Schwarzschild-Couder design, and a camera
based on SiPM (Silicon Photo Multiplier); it will be assembled at the INAF
astronomical site of Serra La Nave on mount Etna (Catania, Italy) within mid
2014, and will start scientific validation phase soon after. The peculiarities
of the optical design and of the SiPM bandpass pushed towards specifically
optimized choices in terms of reflective coatings for both the primary and the
secondary mirror. In particular, multi-layer dielectric coatings, capable of
filtering out the large Night Sky Background contamination at wavelengths
nm have been developed and tested, as a solution for the
primary mirrors. Due to the conformation of the ASTRI SST-2M camera, a
reimaging system based on thin pyramidal light guides could be optionally
integrated aiming to increase the fill factor. An anti-reflective coating
optimized for a wide range of incident angles faraway from normality was
specifically developed to enhance the UV-optical transparency of these
elements. The issues, strategy, simulations and experimental results are
thoroughly presented.Comment: 4 pages, 6 figures. In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All ASTRI contributions
at arXiv:1307.463
An overview on mirrors for Cherenkov telescopes manufactured by glass cold-shaping technology
The cold glass-slumping technique is a low cost processing developed at INAF-Osservatorio Astronomico di Brera for the manufacturing of mirrors for Cherenkov telescopes. This technology is based on the shaping of thin glass foils by means of bending at room temperature. The glass foils are thus assembled into a sandwich structure for retaining the imposed shape by the use of a honeycomb core. The mirrors so manufactured employ commercial off-the-shelf materials thus allowing a competitive cost and production time. They show very low weight, rigidity and environmental robustness. In this contribution we give an overview on the most recent results achieved from the adoption of the cold-shaping technology to different projects of Cherenkov telescopes. We show the variety of optical shapes implemented ranging from those spherical with long radius of curvature up to the most curved free form ones
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